The use of a catheter based percutaneous valved stent has been shown to be feasible in replacing both the human pulmonic and aortic valves. The pulmonic valve was the first to be successfully replaced by a percutaneous approach and is the furthest along in development (FIG. 1A). There are currently two aortic valve products in clinical trials (FIG. 1B and FIG. 1C) and more in development that are deployed percutaneously. While there is a great deal of interest in replacing the mitral valve percutaneously, the anatomy and function of the mitral valve prevents direct application of the current aortic/pulmonic technology.
In addition to the percutaneous catheter-based aortic valve replacement devices illustrated in FIG. 1, there are three other types of replacement valve prosthesis known to the applicants that use different technologies. One known technology, named the Transcatheter Mitral Valve Implantation (TMVI), is being developed by CardiAQ Valve Technologies (CVT). This design is more of a basic stent which lacks a sufficient anchoring mechanism. The TMVI is in a very preliminary design phase and, to date, has not been tested repeatedly with success in animal models. A second known technology is being developed by EndoValve. The EndoValve design is not stent based but relies on a tripod anchoring system with a central supporting strut. A device to be used with this technology will be introduced by minimally invasive surgical techniques. A third known minimally invasive off pump mitral valve replacement device is being developed by Georg Lutter's group at the University of Kiel in Germany. Their design is stent based but requires placement through the apex of the left ventricle (LV). Surgically manipulating the LV apex through a small incision can be relatively dangerous particularly in patients with CHF and IMR. This is a relative negative for that design as it is more desirable to access the mitral valve via the safer and more forgiving lower pressure left atrium. The anchoring mechanism is also awkward in that it relies on a chord from the implant being brought out through the LV apical incision and secured in the closure of that incision. This anchoring strategy also precludes the device ever evolving to the point of being placed via a peripheral blood vessel.
There are also a large group of percutaneous mitral valve repair devices that have been developed to date. The majority of these devices have tried to exploit the proximity of the coronary sinus to the mitral valve annulus to perform some type of “annuloplasty” to limit mitral regurgitation. The basic premise behind all of them is to place a device in the coronary sinus that will shrink the valve orifice and thus decrease mitral regurgitation. However, none of these techniques has shown reproducible efficacy in human trials despite almost 10 years of development work. The most successful percutaneous mitral valve repair technique is EValve's MitraClip® System. This device is used to clip the mitral leaflets together to limit mitral regurgitation. Unfortunately, the clip system has significant down sides. It can be very difficult and tedious to master technically and even in expert hands can take hours to place. Also, it does not eliminate MR; it only limits it. It does not approximate the success of surgical mitral valve repair or replacement and as such is only a temporizing strategy.
The mitral valve replacement platforms described herein are designed to assist patients who suffer from ischemic mitral valve regurgitation (IMR). The majority of patients with IMR would benefit from valve replacement but are too sick to withstand the morbidity of standard valve replacement procedures. This population of patients in the United States alone is estimated to be 1.2 to 2.1 million patients, with approximately 425,000 patients having moderate or severe IMR with heart failure. IMR results from left ventricular (LV) distortions caused by a myocardial infarction (MI) or heart attack. Patients with this disease survive their heart attack but the resulting injury causes the ventricle to dilate and fail over months and years. In many cases this congestive heart failure (CHF) is worsened by IMR. Patients with CHF and IMR can become extremely sick and be very hard to manage medically. Most clinicians agree that a competent mitral valve would make the management of these patients much more straight-forward and cost effective.
Accordingly, there is a significant need for percutaneous mitral valve replacement technologies that are appropriately configured to account for the dimensions and geometry of the mitral valve. It would be advantageous to have a device that can be deployed percutaneously and/or transapically to create a platform at the mitral valve position that reduces the diameter to an appropriate and uniform size/dimension for subsequent percutaneous and/or transapical implantation of a valved-stent. The invention provides several embodiments of such a device.